Aristotle's Politics is a work of political philosophy. The end of the Nicomachean Ethics declared that the inquiry into ethics necessarily follows into politics, and the two works are frequently considered to be parts of a larger treatise, or perhaps connected lectures, dealing with the "philosophy of human affairs." After studying a number of real and theoretical city-state's constitutions, Aristotle classified them according to various criteria. On one side stand the true (or good) constitutions, which are considered such because they aim for the common good, and on the other side the perverted (or deviant) ones, considered such because they aim for the well being of only a part of the city. The constitutions are then sorted according to the "number" of those who participate to the magistracies: one, a few, or many.